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S96 S. A. DAHANUKAR et al., anti-bacterial properties of aromatic oils derived from plants using the agar cup and disc diffusion methods. Hence, Agnihotri and Vaidya 165 have to developed a novel approach to study the anti-bacterial property of certain plants like Eugenia caryophyllus, Thymus vulgaris, Cinnamonum zeylanium and Cuminum cyminum. Volatile components of the hexane extracts of these plants were tested against standard gram positive and gram negative bacteria grown on agar slants and the results were expressed as percentage inhibition of the area of the slants. Of the 4 plants selected, Thymus vulgaris had the most prominent anti-bacterial activity. 14.2. Anti-fungal agents The ethanolic extract of Azadirachta indica leaves demonstrated much more significant antidermatophytic activity as compared to the aqueous extract, when tested in vitro against 88 clinical isolates of dermatophytes using the agar dilution technique. The MIC90 of ethanolic extract was 100 µg/ml whereas that of aqueous extract was 500 µg/ml 166 . Four Siddha drugs viz Nandhi mezhugh, Parangi pattai choornam, Erasa kenthi mezhugu and Vaan mezhugu (in order of efficacy) were found to have significant anti-fungal activity when tested against 14 strains of Candida albicans 167 . Essential oil obtained from the herb of Santolina chamaecyparissus showed significant anti-fungal activity both in vitro (against 13 strains of Candida albicans) and in vivo (experimentally induced vaginal and systemic candidiasis in mice) 168 . It also showed activity against experimentally induced superficial cutaneous mycoses in guinea pigs by the hair root invasion test 169 . Anti-bacterial activity was also observed as seen by its inhibitory effects on the growth of Staphylococcus aureus, Bacillus subtitis, Bacillus caerus and Escherichia coli. Rai 170 screened 17-medicinal plants against the test pathogen, Pestalotiopsis mangiferae and the results revealed that 14 plants had anti-mycotic activity whereas 3-plants, viz., Argemone mexicana, Caesalpinia bonducella and Casia fistula accelerated the growth of the pathogen. Maximum antimycotic activity was shown by Eucalyptus globulus (88%) and Catharanthus roseus (88%) followed by Ocimum sanctum (85.50%), Azadirachta indica (84.66%), Ricinus communis (Erand) (75%) and Lawsonia inermis (74.33%) while the minimum activity was exhibited by Jatropha curcas (10%). The essential oil isolated from the leaves of Aegle marmelos exhibited significant anti-fungal activity against different fungal isolates and 100% inhibition of spore germination of all the tested fungi when evaluated using the spore germination assay. Kinetic studies showed that the inhibition was both concentration as well as time dependent 171 . Four compounds have been isolated from an extract prepared from the fruit rind of Terminalia belerica viz. termilignan, thannilignan (both lignans), 7-hydroxy- 3',4'-(methylenedioxy) flavone and anolignan B. All possessed demonstrable anti-HIV-1, anti-malarial, and anti-fungal activity in vitro 172,173 . The natural xanthones isolated from the fruit hulls of Garcinia mangostana showed good inhibitory activity against the three phytopathogenic fungi, Fusarium vasinfectum, Alternaria tenuis, and Dreschlera oryzae. Substitution in the A and C rings in the derivatives of mangostin obtained by has been shown to modify the bioactivities of the compounds 174 . The petroleum ether, chloroform, acetone and ethanol (95%) extracts of the leaves of Cassia alata also showed significant in vitro anti-fungal activity against various fungi viz. Aspergillus niger, R. japonicum, Candida albicans, C. tropiathis and R. glutinis 175 . The root of Withania somnifera was found to be effective in prolonging the survival of Balb/c mice infected intravenously with Apergillus fumigatus. This protective activity is probably due to the observed increase in phagocytosis and intracellular killing capacity of peritoneal macrophages induced by treatment with Withania somnifera, thus suggesting that the plant has the potential to activate macrophage function in infectious states 176 . 14.3. Anti-viral agents Although initial studies by Thyagarajan et al, 177 with Phyllanthus amarus showed promising results in Hepatitis B carriers, further studies have demonstrated that the plant does not clear the hepatitis B surface antigen (HbsAg) in asymptomatic carriers of the antigen 178 . However, recently, in an in vitro study, the aqueous extract of Phyllanthus amarus was
MEDICINAL PLANTS (NATURAL PRDUCTS) S97 Table 1. Illustrates the other plants that have been evaluated in various models of liver diseases and the parameters selected for their evaluation. Plants/Plant derived agents (Author) Damaging agent (Animals) Parameters of evaluation Methanolic extracts of the seeds of Paracetamol ) Liver function tests (AST, ALT, alkaline Apium graveolens Linn. and ) rats phosphatase, sorbitol dehydrogenase, Hygrophilia auriculata H 268 Thioacetamide ) glutamate dehydrogenase and bilirubin), Hepatic triglycerides, Histopathology. 50% alcoholic extract of Country made liquor ingestion (rats). Liver function tests, Phyllanthus emblica and its isolate, Paracetamol (mice) Histopathology. quercetin 269 Garlic oils 270 Radiocalcium (mice) Hepatic total lipids, triglycerides, phospholipids, free fatty acids Swertia chirata 271 CCl 4 (rats) Liver function tests, Liver glycogen content, Serum cholesterol, Histopathology. Ethyl acetate extract of CCl 4 (rats) Liver function tests, Acacia catechu (katha) 272 Histopathology. Leaf extract of Glycosmis pentaphylla 273 CCl 4 (rats) Liver function tests, Histopathology. Propolis, a natural resin Alcohol and CCl 4 (rats) Liver function tests (AST, ALT), produced by honey bees, Blood and hepatic glutathione levels, rich in flavonoids 274 Hepatic lipid peroxide content, Histopathology. Powdered roots and aerial parts of CCl 4 , paracetamol and Liver function tests Sida rhombifolia and their aque rifampicin (rats) us extracts 41 Plant leaf suspension and methanolic Paracetamol (rats) Liver function tests, extract of Trichopus zeylanicus 275 Histopathology, Hepatic and lipid peroxide contents. Methanolic extract of Trichopus zeylanicus 275 Normal rats Cholerectic activity incubated with the Alexandar cell line, a human hepatocellular carcinoma derived cell line which has the property of secreting the Hepatitis B surface antigen (HbsAg) in the supernatant. The results demonstrated that Phyllanthus amarus was effective in inhibiting the secretion of HbsAg for 48 hrs thus proving its anti-hepatitis B virus property at the cellular level 179 . Glycyrrhizin, a triterpenoid glycoside obtained from Glycyrrhiza glabra (Yasthimadhu) was tested against RNA viruses like the Chandripura virus, Measles virus, Polio vaccine viruses type 1, 2 and 3, Polio wild type viruses 1, 2 and 3 as well as DNA viruses like the Herpes type 1 and 2 viruses in vitro. It inhibited the DNA virus plaque formation at lower concentrations (0.608 mM) while the RNA viruses were inhibited at higher concentrations (1.216 mM) 180 . Premanathan et al, 181 carried out in vitro screening
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